1. Field of the Invention
Aspects of the present invention relate to an optical recording medium, and, more particularly, to a method and apparatus to determine an optimum reproducing condition on a super resolution optical recording medium.
2. Description of the Related Art
Methods of reproducing data from super resolution optical disks are different from those of other existing optical disks. The super resolution disk, that allows a reproduction of information of recorded or previously formed pits, according to the change in an optical refractive index due to a constant temperature increase, has a very rapid reproduction power critical value, as shown in FIG. 1. When a 75 nm length mark (corresponding to a 2T mark) and a 112.5 nm length mark (corresponding to a 3T mark) are recorded by a pickup using a light beam having a wavelength 405 nm and an NA of 0.85, such that a resolution of the pickup is 119 nm (=405 nm/(4×0.85)), a carrier noise ratio (CNR) sharply increases at a reproduction power of about 1.8 mW. It can be seen that a rapid critical phenomenon of the reproduction power has a great influence on the reproduction operation of the super resolution optical disk due to the basic principle of the super resolution optical disk. Thus, determining an optimum reproduction power of the super resolution disk is important.